BGDA Practical Placenta - Maternal Decidua

From Embryology
BGDsmall.jpg
Practical 14: Implantation and Early Placentation | Villi Development | Maternal Decidua | Cord Development | Placental Functions | Diagnostic Techniques | Abnormalities


Uterus

Scheme of Placental Circulation[1]

Human placenta classified as Haemochorial where the chorion comes in direct contact with maternal blood.

During pregnancy:

  • maternal blood volume increases (from non-pregnant state) by about 50%.
  • uterine blood flow increases 10 to 12 fold.
    • Blood flow increase is due to the trophoblast cell invasion of the spiral arteries opening them into blood-filled spaces of the placenta.


Menstrual Changes

  • Endometrium - 3 layers in secretory phase of menstrual cycle: compact, spongy, basal.
  • Myometrium - muscular layer outside endometrium, contracts in parturition.
  • Perimetrium - tunica serosa of the uterus continuous with the peritoneal wall.

Endometrial Layers

  • Compact - implantation occurs in this layer, dense stromal cells, uterine gland necks, capillaries of spiral arteries.
  • Spongy - swollen stromal cells, uterine gland bodies, spiral arteries.
  • Basal - not lost during menstruation or childbirth, own blood supply.

Uterine glands

  • still well-developed and highly active at 6 weeks (GA).
  • gradually regress in length and epithelium height as the first trimester advances.

Decidual Reaction

Maternal Decidua and anchoring villi

Process (decidualization) of endometrial stromal cells (fibroblast-like) change in morphology (polygonal cells) and protein expression and secretion.

  • occurs initially at site of implantation and includes both cellular and matrix changes
  • reaction spreads throughout entire uterus, not at cervix
  • deposition of fibrinoid and glycogen and epithelial plaque formation (at anchoring villi)
  • presence of decidual cells are indicative of pregnancy

Fibrinoid layer - (Nitabuch's layer) is thought to act to prevent excessively deep implantation.

Artery Dilatation - due to extravillous trophoblast cells invading uterine wall and maternal spiral arteries replacing both smooth muscle with fibrinoid material and part of vessel endothelium. There is also a proliferation of maternal blood vessels.

Cervix - at mouth of uterus, secretes mucus (CMP), forms a plug/barrier, mechanical and antibacterial.

Decidua

The endometrium becomes the decidua and forms 3 distinct anatomical regions (at approx 3 weeks)
  • Decidua Basalis at implantation site
  • Decidua Capsularis enclosing the conceptus
  • Decidua Parietalis the remainder of uterus
    • Decidua capsularis and parietalis eventually fuse and uterine cavity is lost about Week 12.
    • decidua capsularis then degenerates
Gray0034.jpg

Historic drawing showing decidua parts

Maternal Blood Flow

Gray0589.jpg


Uterine Arteries
Uterine Blood Supply Uterine Arterial Distribution
Gray1170.jpg Uterine arterial vessel cartoon.jpg


Gray0039.jpg


Maternal Placental Artery Remodelling
Ramsey1972 fig04-16a.jpg Ramsey1972 fig04-16b.jpg Ramsey1972 fig04-16c.jpg Ramsey1972 fig04-16d.jpg Ramsey1972 fig04-16e.jpg
GA 8 weeks GA 16 weeks GA 20 weeks GA 32 weeks term


Maternal blood pressure normally decreases or remains unchanged during pregnancy while both cardiac output and vascular volume are increased. Uterine blood flow changes are principally due to a decrease in uterine vascular resistance. There is also an associated structural enlargement of both the uterine arterial and venous trees, reduced vascular tone (vasodilation) and placenta development.

Uteroplacental blood flow (UPBF) was historically measured by a number of different mathematical calculations and probe methods, currently the method involves transvaginal doppler ultrasonography.

In human singleton pregnancies, uteroplacental blood flow (UPBF) begins at 20–50 ml/min and increases (linearly) to 450–800 ml/min, with twin pregnancy values in excess of 1 l/min.[2]

Uterine Artery Diameter

The following data is from a study of 18 pregnant women using ultrasound and doppler analysis of the uterine artery.[3]

  • GA week 21 doubled (from 1.4 to 2.8 mm).
  • GA week 21 to 30 remained constant (2.9mm).
  • GA week 30 to 36 increased (to 3.4 mm).

Uterine artery mean flow velocity also increased nearly eight times from non-pregnant (8.4 cm/second) to GA week 36 (61.4 cm/second).

Arcuate and Radial Arteries

These branches from the paired uterine arteries also remodel enlarging in lumen diameter between 25 to 220% with either no change or an increase in wall thickness. Arcuate arteries also elongate either by longitudinal growth or by the progressive straightening of these coiled vessels.


Links: ultrasound | cardiovascular


Uterine Vasculature - Non-pregnant, Pregnant and Immediate Post-partum

Uterine and placental vasculature.jpg


Diagrammatic representation of uterine and placental vasculature (red shading = arterial; blue shading = venous) in the non-pregnant, pregnant and immediate post-partum state.

  • Normal pregnancy is characterized by the formation of large arteriovenous shunts (anastomoses) that persist in the immediate post-partum period.
    • bypasses both the uterine capillary network and the intervillous space and regulate the pressure within the maternal blood-filled spaces.
  • Extravillous cytotrophoblast invasion in normal pregnancy (diamonds) extends beyond the decidua into the inner myometrium resulting in the formation of funnels at the discharging tips of the spiral arteries.
  • Pregnancies complicated by severe preeclampsia are characterized by minimal arterio-venous shunts, and thus narrower uterine arteries. Contrast with severe preeclampsia.


Maternal Decidua Interactive Component

Attempt the Quiz - Maternal Decidua  
BGDsmall.jpg

Here are a few simple Quiz questions that relate to Maternal Decidua from the practical.


1

During late pregnancy, which of the following layers of placental membrane is in direct contact with maternal blood?

  the cytotrophoblastic shell
  the syncytiotrophoblast
  the extraembryonic mesoderm
  the intraembryonic mesoderm
  the endothelium of placental blood vessels

2

Which one of the following statements about the maternal decidual reaction is most correct.

  the maternal decidual reaction commences at the site of implantation
  the maternal decidual reaction protects the uterine wall from over implantation
  the maternal decidual reaction spreads through the entire uterus
  the maternal decidual reaction involves the uterine stromal cells
  all of the above refer to the maternal decidual reaction

3

How is the uterine cavity lost?

  decidua basalis and decidua capsularis fuse
  decidua basalis and decidua parietalis fuse
  decidua capsularis and decidua parietalis fuse
  all decidual layers fuse
  none of the above

4

Which maternal arteries are remodelled by trophoblast cells?

 internal iliac artery
  uterine artery
  arcuate arteries
  helicine arterioles
  radial arteries
  spiral arteries

5

Which of the following terms best describes the form of human placental organisation/classification?

  Haemochorial
  Endotheliochorial
  Epitheliochorial


BGDsmall.jpg
Practical 14: Implantation and Early Placentation | Villi Development | Maternal Decidua | Cord Development | Placental Functions | Diagnostic Techniques | Abnormalities

Additional Information: maternal decidua


BGDsmall.jpg
Practical 14: Implantation and Early Placentation | Villi Development | Maternal Decidua | Cord Development | Placental Functions | Diagnostic Techniques | Abnormalities


Additional Information

Additional Information - Content shown under this heading is not part of the material covered in this class. It is provided for those students who would like to know about some concepts or current research in topics related to the current class page.
Placenta and Decidua[4]

The maternal uterine endometrium stromal cells (fibroblast-like) are transformed by steroid hormones (progesterone) and embryonic signals into the decidua.


Human placenta SERPINE2 expression 02.jpg

Immunostained placenta and decidua.[4]

SERPINE2 was extensively detected in decidual cells (dc), cytotrophoblasts, extravillous trophoblasts at the junction zone of the cell column (cc) and anchoring villi (av), and the endothelia of the spiral artery (sa); and weak staining was found in fibrinoids (f) and the villous mesenchyme.


Historic Drawings

Placental Classification

Classification of placenta is on the basis of histological (microscopic) structural organization and layers between fetal and maternal circulation.

Three main groups:

  1. Haemochorial - placenta where the chorion comes in direct contact with maternal blood (human).
  2. Endotheliochorial - maternal endometrial blood vessels are bare to their endothelium and these comes in contact with the chorion (dog, cat).
  3. Epitheliochorial - maternal epithelium of the uterus comes in contact with the chorion, considered as primitive (pig, cow).

The presence of these three differing types of placenta have also been used to describe the pattern mammalian evolution.


Fibrinoid

Exist as 2 forms of extracellular matrix:

  1. Fibrin-type fibrinoid is a maternal blood-clot product which replaces degenerative syncytiotrophoblast
  2. Matrix-type fibrinoid is secreted by invasive extravillous trophoblast cells.

Fibrinoid layer (Nitabuch's layer) is thought to act to prevent excessively deep implantation.

Decidualization

Process of endometrial stromal cells (fibroblast-like) change in morphology (polygonal cells) and protein expression and secretion (specific decidual proteins: prolactin, insulin-like growth factor binding protein-1, tissue factor, interleukin-15, and VEGF).

  1. Estrogen and progesterone - receptive phase, luminal and glandular epithelial cells change in preparation for blastocyst adplantation.
  2. Human Chorionic gonadotropin - luminal epithelium endoreplication leading to epithelial plaque formation.
  3. Human Chorionic gonadotropin - trophoblast invasion and decidualization of human stromal fibroblasts.

Pregnant Uterine Blood Flow

  1. arterial blood supplies the uterus and cervix (arteries, arterioles, capillary network, venules and vein).
  2. spiral arteries supplies the intervillous space (functionally like a large capillary network).
  3. arterial and venous shunts circulation (arteriovenous anastomoses), bypasses both the uterine capillary network and the intervillous space.

See Review[5]

Artery Dilatation

Due to extravillous trophoblast cells invading uterine wall and maternal spiral arteries replacing both smooth muscle with fibrinoid material and part of vessel endothelium. There is also a proliferation of maternal blood vessels.

Anastomoses

During normal pregnancy large anastomoses, arteriovenous "shunts", form that regulate both blood pressure and flow within the placenta. Shunts bypasses both the uterine capillary network and the intervillous space and regulate the pressure within the maternal blood-filled spaces. These shunts persist within the uterus in the initial birth period, and are smaller in severe preeclampsia.

Uterine vascular anastomoses.jpg

Other Changes

  • Endoreplication - rounds of nuclear DNA replication without intervening cell or nuclear division (mitosis).
  • Cytokines - of maternal origin also act on placental development.
  • Natural Killer (NK) cells
    • 30% of all the decidual cells towards the end of the first trimester of pregnancy.
    • Present in the maternal decidua in large numbers (70%, normal circulating blood lymphocytes 15%) close to the extravillous trophoblast cells.
    • Normally have a cytolytic potential against virus-infected and tumor-transformed cells.

Preeclampsia

  • Preeclampsia - describes maternal high blood pressure and protein in the urine after the 20th week (GA) late 2nd or 3rd trimester of pregnancy. This may be due to factors from the placenta.
  • Eclampsia - seizures (convulsions) in a pregnant woman that are not related to a preexisting brain condition.

Terms

Placenta Terms (expand to view) 
  • after-birth - term used to describe the delivery of placenta and placental membranes following birth of the child.
  • allantois - An extraembryonic membrane, endoderm in origin extension from the early hindgut, then cloaca into the connecting stalk of placental animals, connected to the superior end of developing bladder. In reptiles and birds, acts as a reservoir for wastes and mediates gas exchange. In mammals is associated/incorporated with connecting stalk/placental cord fetal-maternal interface.
  • amniocentesis - Clinical term for a prenatal diagnostic test where an ultrasound guided needle is used to extract a sample of the amniotic fluid. Amniocentesis
  • anastomosis - Term used to describe the connection between two tubes. Applied to describe the connection between peripheral blood vessels without an intervening capillary bed.
  • anchoring villi - (stem villi) describes the placental villi (embryonic) that attach to the decidua (maternal) tissue. The tip of the villi consists of a column of trophoblast cells attached to an epithelial plaque.
  • angioblasts form clusters or blood islands on surface of yolk sac.
  • angiogenesis - Term describing the development of new vessels from already existing vessels, this process is secondary to vasculogenesis which is the initial formation of first blood vessels by differentiation of pluripotent mesenchymal cells (extraembryonic mesoderm).
  • capsularis - portion of maternal decidua that covers the conceptus facing towards the uterine cavity.
  • cerebroplacental ratio - (CPR) a doppler ultrasound measurement calculated as the simple ratio between the middle cerebral artery pulsatility index (MCA‐PI) and the umbilical artery pulsatility index (UA‐PI). Fetuses with an abnormal ratio are thought to be a predictor of adverse pregnancy outcome.
  • chorioamnionitis - (CA) An intraamniotic puerperal infection described as having 3 forms: histologic, clinical (clinical chorioamnionitis, IAI), and subclinical. Intraamniotic infection is a common (2-4%) event in labor and the systemic inflammatory response can also lead to preterm birth and neonatal complications.
  • chorion - The extraembryonic membrane generated from trophoblast and extraembryonic mesoderm that forms placenta. chorion and amnion are made by the somatopleure. The chorion becomes incorporated into placental development. The avian and reptilian chorion lies beside the egg shell and allows gas exchange.
  • chorionic cavity - The fluid-filled extraembryonic coelom (cavity) formed initially from trophoblast and extraembryonic mesoderm that forms placenta. chorion and amnion are made by the somatopleure. The chorion becomes incorporated into placental development. The avian and reptilian chorion lies beside the egg shell and allows gas exchange. In humans, this cavity is lost during week 8 when the amniotic cavity expands and fuses with the chorion.
  • chorion frondosum - (frondosum = leafy) The chorion found on conceptus oriented towards maternal blood supply where the majority of villi form and proliferate, will contribute the fetal component of the future placenta.
  • chorion laeve - (laeve = smooth) The smooth chorion found on conceptus away from maternal blood supply (towards uterine epithelium and cavity) with very few villi present.
  • chorionic somatomammotropin - (CSH, human lactogen) A hormone synthesized within the placenta by syncytiotrophoblast cells. This protein hormone (190 amino acid) has a structure is similar to pituitary growth hormone.
  • chorionic villus sampling - (CVS) The taking a biopsy of the placenta, usually at the end of the second month of pregnancy, to test the fetus for genetic abnormalities.
  • coelocentesis - A sampling of extracoelomic fluid usually for an early prenatal diagnostic technique.
  • connecting stalk - the original extra-embryonic mesoderm structure attaching the embryonic disc to the chorion. The placental blood vessels form within this structure.
  • cord blood - (human umbilical cord blood, HUCB) A term used to describe blood collected from the placenta usually after birth. Has been identified as a source of stem cells with potential therapeutic uses and is stored in Cord Blood Banks throughout the world.
  • cord knotting Term describing umbilical or placental cord knotting. This occurs in about 1% prevents the passage of placental blood, pseudoknots also occur usually with no effect.
  • cord presentation - A term used to describe at birth the presence of the umbilical cord between the fetal presenting part and the cervix, with or without membrane rupture.
  • cord prolapse - A term used to describe at birth the descent of the umbilical cord through the cervix alongside (occult) or past (overt) the presenting part in the presence of ruptured membranes (incidence of 0.1% to 0.6%).
  • cotyledon - (Greek, kotyle = a deep cup) In the embryos of seed plants, the "seed leaves," in which nutrients are stored for use after germination. In placental animals, the term is also to describe the leaf-like structure of the placenta surface.
  • cytotrophoblast - The "cellular" trophoblast layer surrounding (forming a "shell") the early implanting conceptus. Beginning at uterine adplantation, proliferation and fusion of these cells is thought to form a second outer trophoblast layer, the syncytiotrophoblast. The cytotrophoblast layer contributes to formation of the placental villi, the functional component of the fetal placenta.
  • decidua basalis - The term given to the uterine endometrium at the site of implantation where signaling transforms the uterine stromal cells (fibroblast-like) into decidual cells. This forms the maternal component of the placenta, the decidualization process gradually spreads through the remainder of the uterus, forming the decidua parietalis.
  • decidua basalis reaction - Term describing the maternal endometrial changes that occur initially at the site of, and following, blastocyst implantation. Seen as a deposition of glycogen, fibrin and proliferation of blood vessels. See also decidualization.
  • decidua capsularis - The term given to the uterine endometrium which has been converted to decidua surrounding the conceptus on the smooth chorion side.
  • decidua parietalis - The term given to the remainder of the uterine endometrium, away from the site of implantation, that gradually becomes comverted to decidua.
  • decidual cell - The uterine stromal cells (fibroblast-like) that differentiate in response to both steroid hormones (progesterone) and embryonic signals. These cells then alter uterine environment to support further embryonic development as well as producing cytokines related to prolactin (PRL) and have an innate immune function.
  • decidual reaction - maternal endometrial reaction invoked in order to block the rapid extension of the implanting syncytium.
  • decidualization - (decidualisation, decidual reaction) The process by which uterine stromal cells differentiate in response to both steroid hormones and embryonic signals into large epitheliod decidual cells. This process is essential for the progress of implantation and establishing fetal-maternal communication.
  • DHEA - (dehydroepiandrosterone, androstenolone) precursor of sex steroid hormones and is converted to testosterone and estradiol. Postnatally, an abundant circulating steroid produced in the adrenal gland. The fetal adrenal cortex produces dehydroepiandrosterone sulfate (DHEA-S) used by the placenta to produce estrogens. DHEA, androstenedione, and testosterone can be metabolized to epiandrosterone, and etiocholanolone. PMID 15635500
  • fetal drug addiction - occurs when drugs used maternally cross the placental barrier and can establish neural/physiological addiction in the unborn fetus. drugs
  • fetal erythroblastosis - (Haemolytic Disease of the Newborn) A clinical term describing an immune response between fetal and maternal blood groups; from fetus Rh+ / maternal Rh-. The leakage of blood from fetus, particularly at birth, causes maternal anti-Rh antibodies, which is then dangerous for a 2nd or future pregnancies.
  • fetal intra-abdominal umbilical vein varix - (FIUV, umbilical vein varix) focal dilatation of the umbilical venous diameter at the level of cord insertion, the dilatation diameter increases linearly with gestational age. Represent about 4% of umbilical cord abnormalities

with an incidence of about 2.8 per 1,000 pregnancies, there is also a rarer form of extra-abdominal varices.PMID 24883288

  • fibrinoid layer - (Nitabuch's layer) A layer formed at maternal/fetal interface during placentation and is thought to act to prevent excessively deep conceptus implantation. Fibrin-type fibrinoid (maternal blood-clot product) and matrix-type fibrinoid (secreted by invasive extravillous trophoblast cells).
  • floating chorionic villi - Term used to describe the placental microanatomy structure of chorionic villi that are not attached to the maternal decidua and float in the maternal blood-filled space (lacunae). Structurally the same as anchoring chorionic villi conceptus side that are attached to the maternal decidua.These villi go through the same stages of development: primary villi - secondary villi - tertiary villi
  • hemotrophic nutrition - Term used to describe in late placenta development the transfer of blood-borne nutrition from maternal to embryo/fetuscompared to early histiotrophic nutrition.
  • heterotopic pregnancy - (Greek, heteros = other) Clinical term for a very rare pregnancy of two or more embryos, consisting of both a uterine cavity embryo implantation and an ectopic implantation.
  • histiotrophic nutrition - Term used to describe in early placenta development the intital transfer of nutrition from maternal to embryo (histiotrophic nutrition) compared to later blood-borne nutrition (hemotrophic nutrition). Histotroph is the nutritional material accumulated in spaces between the maternal and fetal tissues, derived from the maternal endometrium and the uterine glands. This nutritional material is absorbed by phagocytosis initially by blastocyst trophectoderm and then by trophoblast of the placenta. in later placental development nutrition is by the exchange of blood-borne materials between the maternal and fetal circulations, hemotrophic nutrition.
  • Hofbauer cells - Cells found within placental villi connective tissue. Have a role as macrophages of mesenchymal origin with potentially additional functions (remodeling, vasculogenesis, regulation of stromal water content).
  • Human chorionic corticotropin - (hCACTH) placental derived hormone equivilant to corticotropin (ACTH) from the pituitary.
  • Human chorionic gonadotrophin - (hCG) like leutenizing hormone, supports corpus luteum, originally secreted by trophoblast cells.
  • Human chorionic somatommotropin - (hCS, placental lactogen) hormone level increases in maternal blood through pregnancy, decreases maternal insulin sensitivity (raising maternal blood glucose levels and decreasing maternal glucose utilization) aiding fetal nutrition.
  • Template:Hydatiform mole - A uterine tumour with "grape-like" placenta appearance without enclosed embryo formation, arises mainly from a haploid sperm fertilizing an egg without a female pronucleus. It is one form of gestational trophoblastic disease(GTD), a number of abnormalities including hydatiform mole, invasive mole, choriocarcinoma and placental site trophoblastic tumor (PSTT).
  • hysterectomy – clinical term for the surgical removal of the uterus.
  • Langhans layer - cytotrophoblast cell layer.
  • maternal antibodies - antibodies from the mother's immune system that are capable of crossing placental barrier. They can provide immune protection to the embryo, but may also participate in immune disease (fetal erythroblastosis).
  • maternal sinusoids - placental spaces around chorionic villi that are filled with maternal blood. This is the closest maternal/fetal exchange site.
  • Nitabuch's layer - (fibrinoid layer) The layer formed at maternal/fetal interface during placentation and is thought to act to prevent excessively deep conceptus implantation. Fibrin-type fibrinoid (maternal blood-clot product) and matrix-type fibrinoid (secreted by invasive extravillous trophoblast cells).
  • Morbidly adherent placenta (MAP) A general clinical term used to describe the different forms of abnormal placental implantation (Accreta, Increta and Percreta).
  • oligohydramnios - Clinical term for the accumulation a deficiency of amniotic fluid during pregnancy. See also polyhydramnios, an excess of amniotic fluid.
  • persistent right umbilical vein - (PRUV) A placental cord abnormality associated with fetal abnormalities and poor neonatal prognosis. The estimated incidence of persistent right umbilical vein in a low-risk population is 1 : 526. PMID 12047534
  • polyhydramnios - Clinical term for the accumulation of excess amniotic fluid during pregnancy. See also oligohydramnios, a deficiency of amniotic fluid.
  • placenta - (Greek, plakuos = flat cake) The developmental organ formed from maternal and fetal contributions in animals with placental development. In human, the placenta at term is a discoid shape "flat cake" shape; 20 cm diameter, 3 cm thick and weighs 500-600 gm. Placenta are classified by the number of layers between maternal and fetal blood (Haemochorial, Endotheliochorial and Epitheliochorial) and shape (Discoid, Zonary, Cotyledenary and Diffuse). The placenta has many different functions including metabolism, transport and endocrine.
  • placenta accreta - The abnormal placental adherence, either in whole or in part of the placenta with absence of decidua basalis, leading to retention as an after-birth to the underlying uterine wall. The incidence of placenta accreta also significantly increases in women with previous cesarean section compared to those without a prior surgical delivery.
  • placental arteries - (umbilical arteries) In placental animals, the blood vessels which develop within the placental cord carrying relatively deoxygenated blood from the embryo/fetus to the placenta. In humans, there are two placental arteries continuous with the paired internal iliac arteries (hypogastric arteries) arising off the dorsal aortas. At birth this vessel regresses and form the remnant medial umbilical ligament.
  • placental cord - (umbilical cord) The placental cord is the structure connecting the embryo/fetus to the placenta. It is initially extra-embryonic mesoderm forming the connecting stalk within which the placental blood vessels (arteries and veins) form. In human placental cords the placental blood vessels are initially paired, later in development only a single placental vein remains with a pair of placental arteries. This structure also contains the allantois, an extension from the hindgut cloaca then urogenital sinus. Blood collected from the placental cord following delivery is a source of cord blood stem cells.)
  • placental diameter - is measured in the transverse section by calculating the maximum dimensions of the chorionic surface.
  • placental growth factor - (PlGF) A growth factor of the vascular endothelial growth factor (VEGF) family, released from the placental trophoblast cells and other sources that stimulates blood vessel growth.
  • placental malaria - The malarial infection of the placenta by sequestration of the infected red blood cells. This condition can be common in regions where malaria is endemic with women carrying their first pregnancy (primigravida).
  • placenta membranacea - rare placental abnormality characterized by the presence of chorionic villi directly attached to and covering the fetal membranes. Placenta Membranacea
  • placenta previa - placenta overlies internal os of uterus, abnormal bleeding, may require cesarian delivery.
  • placental thickness - is measured at its mid-portion from the chorionic plate to the basilar plate, on a longitudinal plane (less than 4 cm at term). Excludes any abnormalities (fibroids, myometrial contractions, or venous lakes). The placental thickness approximates in millimeters to the weeks of gestation.
  • placental vein - (umbilical vein) In placental animals, the blood vessels which develop within the placental cord carrying relatively oxygenated blood from the placenta to the embryo/fetus. In humans, there are initially two placental veins which fuse to form a single vein. The resence of paired veins in the placental cord can be indicative of developmental abnormalities.
  • placentophagia - Term used to descrbe the maternal ingestion of afterbirth materials (placental membranes and amniotic fluid) that can occur following mammalian parturition (birth).
  • primary villi - (primary chorionic villi) Term describing the earliest stage of embryonic placenta development. In humans, the conceptus during week 2 this first stage of chorionic villi development consists of only the trophoblastic shell cells (syncitiotrophoblasts and cytotrophoblasts) forming finger-like extensions into maternal decidua. Initially these finger-like projections cover the entire surface of chorionic sac and later become restricted to the placental surface. The villi stages are ongoing as the placenta continues to grow through both the embryonic and fetal development.
  • pre-eclampsia - During pregnancy a combination of high blood pressure, protein in urine and fluid retention resulting in maternal sudden excessive swelling of the face, hands and feet. Eclampsia is the subsequent development of convulsions, kidney failure, liver failure, clotting problems or mortality.
  • Rh alloimmunization - feto-maternal haemorrhage generally in late pregnancy results in an Rh-negative woman becoming sensitised to Rh-positive fetal cells that enter her circulation. Clinically treated with anti-D immune globulin prophylaxis, alloimmunization occurs in 9–10% of at-risk pregnancies. immune
  • secondary villi - (secondary chorionic villi) Term describing the second stage of embryonic placenta development. In humans, the conceptus during week 3 onward this stage of chorionic villi development consists of the trophoblastic shell cells (syncytiotrophoblast and cytotrophoblasts) filled with extraembryonic mesoderm forming finger-like extensions into maternal decidua. Initially these finger-like projections cover the entire surface of chorionic sac and later become restricted to the placental surface. The villi stages are ongoing as the placenta continues to grow through both the embryonic and fetal development. Placental villi stages: primary villi - secondary villi - tertiary villi
  • syncytiotrophoblast - A multinucleated cell currently thought to form by the fusion of another trophoblast cell the cytotrophoblasts, within the trophoblast layer (shell) of the implanting conceptus. In early development, these cells mediate implantation of the conceptus into the uterine wall and secrete the hormone (Template:Human Chorionic Gonadotrophin, hCG) responsible for feedback maintainance of the corpus luteum (in maternal ovary) and therefore maintaining early pregnancy.
  • trophoblast - (trophectoderm, Greek, trophe = "nutrition" and blast = a primordial cell) cells that firstly support adplantation, implantation and endocrine support of pregnancy. Contribute to the extraembryonic tissues, fetal placenta and membranes. Initially form 2 populations individual cytotrophoblast cells and their fused multinucleate syncytiotrophoblast cells.
  • Twin-twin transfusion syndrome - (TTTS) in monozygotic twins with monochorionic and diamniotic placenta, with intrauterine blood transfusion from one twin (donor) to another twin (recipient) where there is an imbalance of blood flow from the donor twin to the recipient twin. Clinically diagnosed by the alternate presence of polyhydramnios in one fetus and oligohydramnios in the co-twin, occurs in about 10% of monochorionic twins.
  • umbilical cord (placental cord) fetal attachment cord 1-2 cm diameter, 30-90cm long, covered with amniotic attached to chorionic plate, umbilical vessels (artery, vein) branch into chorionic vessels. Vessels anastomose within the placenta.
  • umbilical vein varix - (fetal intra-abdominal umbilical vein varix, FIUV) focal dilatation of the umbilical venous diameter at the level of cord insertion, the dilatation diameter increases linearly with gestational age. Represent about 4% of umbilical cord abnormalities

with an incidence of about 2.8 per 1,000 pregnancies, there is also a rarer form of extra-abdominal varices. PMID 24883288

  • vasculogenesis - formation of first blood vessels by differentiation of pluripotent mesenchymal cells (extraembryonic mesoderm) followed by angiogenesis which is the development of new vessels from already existing vessels.
  • vasculosyncytial membranes - localised areas of the placental villous membrane where the barrier thickness separating maternal and fetal circulations is reduced to as little as 1-2 microns. PMID 1287078
  • villi - Plural of villus, which is a thin projection from a surface. The term in development is used to describe the individual functional units together of the fetal placenta.
  • virus - small infectious agents that may cross the placental barrier. Can infect embryo and/or placenta and cause developmental abnormalities. (e.g. cytomegalovirus, rubella, measles).
  • Wharton's jelly - placental cord (umbilical cord) gelatinous connective tissue composed of myofibroblast-like stromal cells, collagen fibers, and proteoglycans. Increases in volume (myxomatous, connective tissue embedded in mucus) at parturition (birth) to assist closure of placental blood vessels. Matrix cells from Wharton's jelly have recently been identified as a potential source of mesenchymal stem cells (MSC), also called mesenchymal stromal cell. This placental cord substance is named after Thomas Wharton (1614-1673) an English physician and anatomist who first described this placental tissue.
Other Terms Lists  
Terms Lists: ART | Birth | Bone | Cardiovascular | Cell Division | Endocrine | Gastrointestinal | Genital | Genetic | Head | Hearing | Heart | Immune | Integumentary | Neonatal | Neural | Oocyte | Palate | Placenta | Radiation | Renal | Respiratory | Spermatozoa | Statistics | Tooth | Ultrasound | Vision | Historic | Drugs | Glossary

References

  1. Slator PJ, Hutter J, McCabe L, Gomes ADS, Price AN, Panagiotaki E, Rutherford MA, Hajnal JV & Alexander DC. (2018). Placenta microstructure and microcirculation imaging with diffusion MRI. Magn Reson Med , 80, 756-766. PMID: 29230859 DOI.
  2. Osol G & Mandala M. (2009). Maternal uterine vascular remodeling during pregnancy. Physiology (Bethesda) , 24, 58-71. PMID: 19196652 DOI.
  3. Palmer SK, Zamudio S, Coffin C, Parker S, Stamm E & Moore LG. (1992). Quantitative estimation of human uterine artery blood flow and pelvic blood flow redistribution in pregnancy. Obstet Gynecol , 80, 1000-6. PMID: 1448242
  4. 4.0 4.1 Chern SR, Li SH, Chiu CL, Chang HH, Chen CP & Tsuen Chen EI. (2011). Spatiotemporal expression of SERPINE2 in the human placenta and its role in extravillous trophoblast migration and invasion. Reprod. Biol. Endocrinol. , 9, 106. PMID: 21806836 DOI.
  5. Gyselaers W & Peeters L. (2013). Physiological implications of arteriovenous anastomoses and venous hemodynamic dysfunction in early gestational uterine circulation: a review. J. Matern. Fetal. Neonatal. Med. , 26, 841-6. PMID: 23339488 DOI.


BGDsmall.jpg
Practical 14: Implantation and Early Placentation | Villi Development | Maternal Decidua | Cord Development | Placental Functions | Diagnostic Techniques | Abnormalities